Tuna at Tsukiji Fish Market

Buyers examine tuna lining the floor of Tsukiji Fish Market in Tokyo, Japan. Ounce per ounce, tuna is one of the most valuable varieties of seafood. In 2012, a single 593lb bluefin tuna sold for $736,000 in a Japanese market. Not surprisingly, populations of bluefin tunas have declined to very low levels, and the species is listed as endangered.